Applicant claims priority from U.S. Provisional Application Ser. No. 61/122,976 which was filed on Dec. 16, 2008. That application is incorporated by reference hereinto in its entirety.
The present disclosure relates to gasket or seal assemblies for use in providing a liquid tight seal between an opening in a structure and a pipe. More particularly, the present disclose relates to a sealing assembly having a liquid-filled seal for sealing between an associated structure (e.g., a concrete structure, a manhole, a wet well, etc.) and a liquid-carrying pipe, which provides a dynamic seal with the pipe.
Compression-type connectors or seals, such as those made of rubber or other resilient materials, have been used for many years in sanitary and storm sewer construction for providing a water tight connection between pipes and various sewer or storm structures, and particularly concrete structures such as manholes, wet wells, and other structures used in water conveyance systems. Various types and designs of connectors and seals have been employed over these many years for purposes of improving the water tight performance and sealing characteristics. Despite many advances, compression designs continue to be challenged when used in association with a pipe (whether made of concrete, plastic, iron or other known materials) that can vary beyond tolerances and/or the sealing tolerance of the connector or seal employed with it.
There are two standard techniques typically used when mounting a conventional compression-type seal within an opening in a water conveying structure or member. In a first technique, one radial end of the seal is embedded in the conveying structure when the structure is formed in a casting operation. As such, the seal is integrally joined to the cast member during the casting operation as the cast member is being formed, for example, at a production facility. The second technique is to mount the seal into a recess, such as a groove, formed in a sidewall of the cast member. The opening can be formed either during the casting operation or through a coring operation that occurs after casting but before installation of the seal. In either case, after attachment of the seal to the cast member, the cast member is ready to receive a pipe. An inner radial portion of the seal serves as the pipe engaging portion, the pipe being inserted into the seal so that the pipe engaging portion encircles the exterior surface of the pipe.
The profiles of such seals have heretofore been either solid or defining empty cavities to produce a mechanical softness that reduces the coupling force required (i.e., the force required to insert the pipe into the seal) and enhances the sealing surface characteristics. These conventional profiles have been very effective at sealing with the pipe when a smooth, uniform and concentric outside diameter is provided on the pipe, as is often found when the pipe is formed of materials such as reinforced concrete, ductile iron, spun fiberglass, clay pipe materials, etc. These types of seals have also been adequate for use with flexible pipe, such as PVC or PE, but only where the pipe maintains a smooth and uniform diameter, and also has been properly bedded relative to the cast member so that the outside dimension of the pipe does not change or deflect over time due to movement, such as ground settlement. Another problem occurs when the pipe is oversized in relation to the opening defined in a concrete structure, such as a water conveying structure or member. To remedy this problem, a particularly flexible seal is required.
Conventional designs typically rely on deflection of a rubber or resilient profile within a defined annular space to effect the seal between the outside diameter of the pipe and the inside surface of a structural opening, such as a concrete structure. However, flexible piping materials are being used more and more in direct burial applications in large sizes, such as those exceeding 48 inches in diameter. Also, the criteria specified in ASTM F2510 standard allows for a 5% deflection. This can create the reality of an installation exceeding the connector or seal tolerance. Conventional designs typically suffer a loss of compression when the pipe exceeds a +/−0.25 inch tolerance, which can create a failure requiring a repair or re-excavation. Loss of compression is a particular problem when undersized pipes or piping materials are utilized.
As can be appreciated, this places a large responsibility on the installer requiring him or her to take adequate steps to minimize any long-term deflection in the outside diameter of the flexible pipe material. Moreover, in situations where the pipe does not exhibit a good sealing surface, a dimension within acceptable tolerances, or creeps beyond the sealing limits of a particular seal or connector, a leak is more likely to develop over time. In these situations, conventional extrusion or molded seals for precast members do not always exhibit proper sealing characteristics, particularly over time.
Also, due to the quarter inch tolerance used for most conventional compression connectors or seals, the seal itself and the equipment designed to hold the seal in position during the casting of structures, such as concrete structures, is required to be very exact and is usually available in 0.50″ (half inch) increments. Accordingly, having an inventory covering a full range of sizes from 1.00 inch through over 100.00 inches adversely leads to large inventory related costs.